266 Annals Entomological Society of America  [Vol. VII, 
IV: Foon:’: 
In most of the literature one finds the larve of the old 
family Hydropsychidze spoken of as carnivorous, but Siltala 
(1907) gives the following general statements. ‘The larve of the 
true Hydropsychide are less exclusively carnivorous than 
those of the other campodeoid larve. Both animal and 
vegetable food are found, remains of insects, Crustacea, algal 
filaments, pieces of moss and phanerogam leaves, also pollen 
grains of Conifers.’”’ In an earlier paper (1910) he speaks of 
their ability to utilize hard vegetable stuff, gnawing grooves 
nearly 8 cm. deep in the logs of a bridge. 
“The data were insufficient in the case of the Family Phil- 
opotamide to form any judgment. The Polycentropide are 
purely carnivorous, eating insects, Cladocera and Ostracods.” 
He also points out that a relation exists between the struc- 
ture of the mandibles and the kind of food. He extends 
Ulmer’s (1902) observation that forms with blunt-toothed 
mandibles are herbivorous and those provided with sharp teeth 
are carnivorous, and points out the importance of the presence 
or absence on the mandibles of a median tuft of hairs. All 
forms with the median tuft on both mandibles are herbivorous; 
those lacking it are either exclusively carnivorous or at least 
eat as much animal as vegetable food; larve with the tuft 
only on the left mandible vary in respect to their food and among 
them are found carnivorous, herbivorous and omnivorous forms. 
My results in regard to the food of the larve are based 
entirely on observations upon freshly killed animals taken from 
their natural habitat. The alimentary canal was removed 
immediately after the collecting trip and examined at once, or 
placed in four per cent formalin for later study. 
Collections of Hydropsyche larvae were made on Novem- 
ber 14, 1912, November 21, November 30, January 31, 1913, 
February 18, March 20, April 12, May 6, June 2 and July 7. © 
As many as five specimens were always examined, and in some 
cases as many as ten. The food as stated by Siltala was made 
up of both animal and vegetable matter. There was, however, a 
seasonal difference; in the fall and winter diatoms formed the 
bulk of the food, and in the spring and summer animal food 
predominated; while at all times algal filaments were present 
in moderate amount. 
